As a battery apparatus mountable on an electronic equipment, there is provided one which is provided with a case having a predetermined width, thickness and length, a battery cell housed in the inside of the case, and a battery-side terminal disposed at the surface of the case and electrically connected to the battery cell, and which is inserted into a battery housing chamber of the electronic equipment in the direction of the length so that the battery-side terminal makes connection with a housing chamber-side terminal of the battery housing chamber (see for example Japanese Patent No. 2508447).
However, in the above-mentioned battery apparatus and the electronic equipment, if a battery apparatus having a smaller contour dimension than the shape of a battery housing chamber is inserted into the battery housing chamber, the battery apparatus is unstable in the battery housing chamber, thus failing to use suitably. That is, there is the disadvantage that it is impossible to selectively use a plurality of types of battery apparatuses having different contour dimensions, namely, different capacities.